Many different materials have been used in making knit fabrics for use in, for example, garments. It is often desirable that such fabrics have a combination of desirable properties including one or more of the following: dimensional stability, heat-set properties, capability to be made stretchable in one or both dimensions, chemical, heat resistant, abrasion resistant, tenacity, etc. It is also often important that such fabrics be able to withstand hand or machine washing without significantly degrading one or more of the aforementioned properties. Further, increased throughput with reduced defects, e.g. fiber breakage, is sometimes desirable. For some clothing applications, e.g. garments such as bras, swimsuits, intimate apparel, and the like, it is beneficial if the knitted fabric is capable of being molded i.e., become set into a shape conforming to a three-dimensional mold when subjected to heat without substantial distension of the structure of the fabric. Unfortunately, the prior materials often suffer from one or more deficiencies in the aforementioned properties. In addition, the prior materials may limit the knit process in some way, e.g., production may be limited to a pulley feeding system as opposed to an eyelet system.
Improved fabrics have now been discovered which often have a balanced combination of desirable properties including moldability. These compositions may also allow for improved processability in some applications. The fabric of the present invention is typically a knit fabric comprising elastic Fibers. The elastic fibers comprise the reaction product of at least one ethylene polymer and at least one crosslinking agent. The fibers are characterized by an amount of crosslinking, such that the fabric is capable of being molded. The ethylene polymer is
(A) an ethylene/α-olefin interpolymer, wherein the ethylene/α-olefin interpolymer has one or more of the following characteristics:                (1) an average block index greater than zero and up to about 1.0 and a molecular weight distribution, Mw/Mn, greater than about 1.3; or        (2) at least one molecular fraction which elutes between 40° C. and 130° C. when fractionated using TREF, characterized in that the fraction has a block index of at least 0.5 and up to about 1; or        (3) an Mw/Mn from about 1.7 to about 3.5, at least one melting point, Tm, in degrees Celsius, and a density, d, in grams/cubic centimeter, wherein the numerical values of Tm and d correspond to the relationship:Tm>−2002.9+4538.5(d)−2422.2(d)2; or        (4) an Mw/Mn from about 1.7 to about 3.5, and is characterized by a heat of fusion, ΔH in J/g, and a delta quantity, ΔT, in degrees Celsius defined as the temperature difference between the tallest DSC peak and the tallest CRYSTAF peak, wherein the numerical values of ΔT and ΔH have the following relationships:ΔT>−0.1299(ΔH)+62.81 for ΔH greater than zero and up to 130 J/g,ΔT≧48° C. for ΔH greater than 130 J/g,        
wherein the CRYSTAF peak is determined using at least 5 percent of the cumulative polymer, and if less than 5 percent of the polymer has an identifiable CRYSTAF peak, then the CRYSTAF temperature is 30° C.: or                (5) an elastic recovery, Re, in percent at 300 percent strain and 1 cycle measured with a compression-molded film of the ethylene/α-olefin interpolymer, and has a density, d, in grams/cubic centimeter, wherein the numerical values of Re and d satisfy the following relationship when ethylene/α-olefin interpolymer is substantially free of a cross-linked phase:Re>1481−1629(d); or        (6) a molecular fraction which elutes between 40° C. and 130° C. when fractionated using TREF characterized in that the fraction has a molar comonomer content of at least 5 percent higher than that of a comparable random ethylene interpolymer fraction eluting between the same temperatures, wherein said comparable random ethylene interpolymer has the same comonomer(s) and has a melt index, density, and molar comonomer content (based on the whole polymer) within 10 percent of that of the ethylene/α-olefin interpolymer; or        (7) a storage modulus at 25° C., G′(25° C.), and a storage modulus at 100° C., G′(100° C.), wherein the ratio of G′(25° C.) to G′(100° C.) is in the range of about 1:1 to about 9:1; or        
(B) a homogeneously branched ethylene polymer; or
(C) a mixture thereof.
The ethylene/α-olefin interpolymer characteristics (1) through (7) above are given with respect to the ethylene/α-olefin interpolymer before any significant crosslinking, i.e., before crosslinking. The ethylene/α-olefin interpolymers useful in the present invention are usually crosslinked to a degree to obtain the desired properties. By using characteristics (1) through (7) as measured before crosslinking is not meant to suggest that the interpolymer is not required to be crosslinked—only that the characteristic is measured with respect to the interpolymer without significant crosslinking. Crosslinking may or may not change each of these properties depending upon the specific polymer and degree of crosslinking.